1. Field of the Invention
The present invention relates to a polarization control device.
2. Description of the Related Art
Japanese Patent No. 4410149 discloses a polarization rotation device. The polarization rotation device includes a first core layer having a rectangular cross section, a second core layer having a rectangular cross section, and a cladding layer. The first core layer is covered with the second core layer, which is covered with the cladding layer. A refractive index of the first core layer is greater than those of the second core layer and the cladding layer, and the refractive index of the second core layer is greater than that of the cladding layer. A central axis of the first core layer in the light propagation direction differs from that of the second core layer in the light propagation direction. The length of the second core layer in the light propagation direction is set such that polarization of linearly polarized light is rotated 90 degrees while propagating through the first and second core layers.